PCR Test for the Detection of Contagious Equine Metritis by Taylorella

1. Purpose of the test
ADIAVET™ CEMO TAYLORELLA REAL TIME kit is intended to detect Taylorella equigenitalis and
Taylorella asinigenitalis using real-time Polymerase Chain Reaction (PCR) technology from swab and
semen specimen of equine and bacterial culture.
2. Taylorella
Contagious equine metritis (CEM) is an inflammatory disease of the proximal and distal reproductive
tract of the mare caused by Taylorella equigenitalis (OIE 2012). Infection in the pregnant mare may be
symptomatic or asymptomatic (Timoney, 2011). Symptomatically infected mares may or may not
present with an intermittent vaginal discharge over the course of pregnancy. Abortion at approximately
7 to 8 months of gestation is a very rare sequel to infection.
Stallions are not strictly infected by T. equigenitalis as the organism is a smegma-associated commensal
and merely colonises predilection sites in the external genitalia without eliciting an immune response
or clinical signs (Schulman et al ., 2013).
Carrier mares and stallions act as reservoirs of T. equigenitalis, but stallions, because they mate with
numerous mares, play a much more important role in dissemination of the bacterium (OIE, 2012).
CEM is a OIE notified disease. The diagnostic is standardized (e.g. OIE Terrestrial manual, 2012,
Chapter 2.5.2).
Another species of Taylorella, Taylorella asinigenitalis, has been isolated from male donkeys and horse
mares and stallions in the United States of America and a number of European countries.
Other causes of endometritis include Pseudomonas aeruginosa and Klebsiella pneumoniae (cf
ADIAVET™ CEMO KLEB/PSEUDO REAL TIME).
CEM is diagnostic by swabbing genital tractus of mare and stallion. Swab is sending to diagnostic
laboratory into Amies transport medium with charcoal. This shipment condition allows the protection
of T. equigenitalis and T. asinigenitalis that are sensitive bacteria to oxygen.
Taylorella are Gram-negative microaerophilic non motile coccobacilus. Isolation of Taylorella requires
enriched media and a standard incubation time of at least 7 days is advisable before certifying cultures
negative for T. equigenitalis (OIE, 2012).
Serology has limited application and sero-conversion is reported as a transient feature associated with
acute endometritis in the mare, and absent in stallions (Schulman et al., 2013).
A variety of discriminatory real time PCR assays for rapid, sensitive and specific detection for
T. equigenitalis and T. asinigenitalis directly from genital swabs without a need for additional bacterial
isolation have been developed. PCR addresses most of the associated short-comings of bacteriology
with fewer false negatives due to enhanced sensitivity and discriminatory specificity in detecting
bacterial presence despite factors including lower bacterial concentrations and heavily contaminated,
damaged or delayed samples (Schulman et al., 2013).
3. Description and purpose of the test
This test is based on enzymatic gene amplification or PCR technology.
Amplified products are detected in real-time thanks to a specific labelled hydrolysis probe (5’-
exonulease technology).
The ADIAVET™ CEMO TAYLORELLA REAL TIME kit enables the simultaneous detection of:
– T. equigenitalis (probe labelled in FAM),
– T. asinigenitalis (probe labelled in Cy5),
– an internal control of amplification step specific from an exogenous DNA (probe labelled
with a fluorochrome read in the same spectra as VIC and HEX).
Adiagene recommends using this test with DNA purification kits (Adiagene, Qiagen and Macherey-
Nagel). Other purification kits can be used if they have been validated by the user.